Trailer Coding in Engine Control Unit (ECU)

Hello everyone,

The instructions for my Westfalia electric drive kit (the version with the Westfalia control unit, not the one with the original control unit), which was installed in September 2014, completely describe the activation process and include the usual entries in the gateway and parking assist system. ABS/ESP is automatically enabled on this generation.

Yesterday, I went through the coding assistant on the engine control unit. Interestingly, there's a configuration bit there labeled "trailer."

I had studied the instructions for many electronic modules before I bought the Westfalia part. Most of them are quite universal for the platform. Some (not Westfalia) require that you also perform a corresponding coding in the engine control unit for certain cars (e.g., Passat, Octavia was never included).

Putting it all together, I'm now wondering: What does this bit do in the engine control unit? Is it a good idea to set it if you have a trailer controller whose instructions don't require it?

The control unit itself cannot be diagnosed with VCDS (only with a Westfalia tester), but it responds correctly and the Autoscan function shows its proper operation at the top (while indicating "not reachable" at the bottom). All functions are working as they should: The parking assist system detects a trailer, the body control module deactivates the interior lights on the vehicle, and the ESP signals trailer stabilization when turned on.

According to this, the car "knows" when a trailer is attached. What should the engine control unit (ECU) do with that information? It certainly won't release more power or torque... Hopefully, it will also run the radiator fan at full speed in case of overheating, even without a trailer.

Best regards,

Jan.

Quote:

What should the MSG (Motor Control System) conclude from this? ... Hopefully, it will also fully activate the radiator fan in case of overheating, even without a trailer attached.

The threshold values for when to switch to higher or lower cooling power can be lowered to provide a bit more reserve capacity when needed.

However, that's purely speculation on my part.

Best regards, Rainer.

Hi,

Here's what I was also thinking: With some models, when a factory-installed trailer hitch is installed, other components are used, such as more powerful fans or similar parts. In that context, the bit might be there to inform the control unit about this specific configuration.

Could someone who has a factory-installed tow hitch on their PQ35 car check if the relevant bit is set in the coding (the assistant knows which one it is)?

Best regards,

Jan.

Jan6K wrote:

... Could someone who has a factory-installed tow hitch on their PQ35 vehicle check if the relevant bit is set in the coding (the assistant knows which one it is)? ...

Does an MQB platform also help you?
That bit is set.


But let's get back to the 1Z.
No, you shouldn't set that bit!
Why?
The 1Z comes with various fan configurations (with one fan, with two, and several sub-versions of the latter). If you haven't adjusted the cooling system, you shouldn't change anything there.

I am aware of the following equipment options for the 140 hp TDI engine:
1. -> Right side: 295mm with 200W, Left side: 360mm with 220W (for vehicles with Climatronic).
2. -> right side, 360mm with 300W, and left side, 365mm with 300W (vehicles with Climatic and trailer hitch).

Beim 110PS Motor habe ich folgende Konfigurationen gefunden:
1. -> rechts 293mm mit 150W und links 360mm mit 220W
2. -> rechts 293mm mit 150W und links 360mm mit 300W
Leider habe ich dazu keine genauen Ausstattungsinformationen.

Hi,

ah - also doch! Man sagt dem Auto mit dem Bit, ob das AHK-relevante Zeugs verbaut ist.

Ist es natürlich nicht, also bleibt das Bit.

Ich schaue mir mal bei Gelegenheit die beiden Lüfter an, ob man da Leistungswerte lesen kann.

Viele Grüße,

Jan